github.com/fff-chain/go-fff@v0.0.0-20220726032732-1c84420b8a99/core/state_prefetcher.go (about)

     1  // Copyright 2019 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package core
    18  
    19  import (
    20  	"sync/atomic"
    21  
    22  	"github.com/fff-chain/go-fff/consensus"
    23  	"github.com/fff-chain/go-fff/core/state"
    24  	"github.com/fff-chain/go-fff/core/types"
    25  	"github.com/fff-chain/go-fff/core/vm"
    26  	"github.com/fff-chain/go-fff/params"
    27  )
    28  
    29  const prefetchThread = 2
    30  
    31  // statePrefetcher is a basic Prefetcher, which blindly executes a block on top
    32  // of an arbitrary state with the goal of prefetching potentially useful state
    33  // data from disk before the main block processor start executing.
    34  type statePrefetcher struct {
    35  	config *params.ChainConfig // Chain configuration options
    36  	bc     *BlockChain         // Canonical block chain
    37  	engine consensus.Engine    // Consensus engine used for block rewards
    38  }
    39  
    40  // NewStatePrefetcher initialises a new statePrefetcher.
    41  func NewStatePrefetcher(config *params.ChainConfig, bc *BlockChain, engine consensus.Engine) *statePrefetcher {
    42  	return &statePrefetcher{
    43  		config: config,
    44  		bc:     bc,
    45  		engine: engine,
    46  	}
    47  }
    48  
    49  // Prefetch processes the state changes according to the Ethereum rules by running
    50  // the transaction messages using the statedb, but any changes are discarded. The
    51  // only goal is to pre-cache transaction signatures and snapshot clean state.
    52  func (p *statePrefetcher) Prefetch(block *types.Block, statedb *state.StateDB, cfg vm.Config, interrupt *uint32) {
    53  	var (
    54  		header = block.Header()
    55  		signer = types.MakeSigner(p.config, header.Number)
    56  	)
    57  	transactions := block.Transactions()
    58  	sortTransactions := make([][]*types.Transaction, prefetchThread)
    59  	for i := 0; i < prefetchThread; i++ {
    60  		sortTransactions[i] = make([]*types.Transaction, 0, len(transactions)/prefetchThread)
    61  	}
    62  	for idx := range transactions {
    63  		threadIdx := idx % prefetchThread
    64  		sortTransactions[threadIdx] = append(sortTransactions[threadIdx], transactions[idx])
    65  	}
    66  	// No need to execute the first batch, since the main processor will do it.
    67  	for i := 0; i < prefetchThread; i++ {
    68  		go func(idx int) {
    69  			newStatedb := statedb.Copy()
    70  			gaspool := new(GasPool).AddGas(block.GasLimit())
    71  			blockContext := NewEVMBlockContext(header, p.bc, nil)
    72  			evm := vm.NewEVM(blockContext, vm.TxContext{}, statedb, p.config, cfg)
    73  			// Iterate over and process the individual transactions
    74  			for i, tx := range sortTransactions[idx] {
    75  				// If block precaching was interrupted, abort
    76  				if interrupt != nil && atomic.LoadUint32(interrupt) == 1 {
    77  					return
    78  				}
    79  				// Convert the transaction into an executable message and pre-cache its sender
    80  				msg, err := tx.AsMessage(signer)
    81  				if err != nil {
    82  					return // Also invalid block, bail out
    83  				}
    84  				newStatedb.Prepare(tx.Hash(), header.Hash(), i)
    85  				precacheTransaction(msg, p.config, gaspool, newStatedb, header, evm)
    86  			}
    87  		}(i)
    88  	}
    89  }
    90  
    91  // precacheTransaction attempts to apply a transaction to the given state database
    92  // and uses the input parameters for its environment. The goal is not to execute
    93  // the transaction successfully, rather to warm up touched data slots.
    94  func precacheTransaction(msg types.Message, config *params.ChainConfig, gaspool *GasPool, statedb *state.StateDB, header *types.Header, evm *vm.EVM) {
    95  	// Update the evm with the new transaction context.
    96  	evm.Reset(NewEVMTxContext(msg), statedb)
    97  	// Add addresses to access list if applicable
    98  	ApplyMessage(evm, msg, gaspool)
    99  }